Absorbent core with absorbent material pattern

ABSTRACT

A substantially planar absorbent core ( 28 ) extending in a transversal direction (x) and a longitudinal direction (y), and comprising a core wrap ( 16, 16 ′) enclosing an absorbent material ( 60 ) substantially free of cellulose fibers, the absorbent material forming a pattern of discrete absorbent material areas. The pattern comprises transversally-orientated areas ( 752 ) and longitudinally-orientated areas ( 754 ). The absorbent core may further comprise at least two longitudinally-orientated channel-forming areas ( 26 ).

FIELD OF THE INVENTION

The invention relates to absorbent cores for personal hygiene absorbentarticles such as, but not limited to, baby diapers, training pants,feminine pads or adult incontinence products.

BACKGROUND OF THE INVENTION

Absorbent articles for personal hygiene, such as disposable babydiapers, training pants for toddlers or adult incontinenceundergarments, are designed to absorb and contain body exudates, inparticular urine. These absorbent articles comprise several layersproviding different functions, typically including a topsheet, abacksheet and in-between an absorbent core, among other layers.

The absorbent core should be able to absorb and retain the exudates fora prolonged amount of time, for example overnight for a diaper, minimizere-wet to keep the wearer dry, and avoid soiling of clothes or bedsheets. The majority of currently marketed absorbent cores comprise asabsorbent material a blend of comminuted wood pulp cellulose fibers withsuperabsorbent polymers (SAP) in particulate form, also called absorbentgelling materials (AGM), see for example U.S. Pat. No. 5,151,092(Buell).

Absorbent articles having a core consisting essentially of SAP asabsorbent material (so called “airfelt-free” cores) have also beenproposed. WO95/11652 (Tanzer) discloses absorbent articles which includesuperabsorbent material located in discrete pockets. US2002095127 (Fish)discloses a laminate structure that is formed from a first substrate, asecond substrate, and discrete regions of particles sandwichedtherebetween. In particular, the first and second substrates are bondedtogether at certain portions such that bonded portions and unbondedportions are formed. The unbonded portions form pockets that contain theparticles. The pockets have a length-to-width ratio of greater thanabout 2. WO2008/155699 (Hundorf) discloses an absorbent core comprisingfirst and second absorbent layers each comprising an absorbentparticulate polymer material such that the absorbent particulate polymermaterial is substantially continuously distributed across an absorbentparticulate polymer material area. WO2012/052172A1 (Van Malderen)discloses absorbent structures comprising a carrier layer, an auxiliarylayer and an absorbent material there between wherein substantiallypermanent primary attachments and substantially temporary secondaryattachments join the carrier layer and auxiliary layer at leastpartially together, whereby the substantially temporary secondaryattachments are loosened as a result of exposing the absorbent structureto a liquid whereas the substantially permanent primary attachmentsremain substantially intact. WO2012/170778 (Rosati et al., see alsoWO2012/170779, WO2012/170781 and WO2012/170808) discloses absorbentstructures that comprise superabsorbent polymers, optionally acellulosic material, and at least a pair of substantially longitudinallyextending absorbent material free zones that can form channels as theabsorbent structure absorb a fluid.

While the previously proposed absorbent cores can provide goodabsorbency capacity, there is a continuous need to improve theproperties of cores in a cost effective manner. In particular there is acontinuous need to improve wearing comfort, increase production speedand reduce raw material usage while keeping optimal fluid managementproperties.

SUMMARY OF THE INVENTION

The invention is directed at a substantially planar absorbent coreextending in a transversal direction and a longitudinal direction. Theabsorbent core comprises a core wrap enclosing an absorbent materialwhich is substantially free of cellulose fibers. The absorbent materialforms a pattern of discrete absorbent material areas. The patterncomprises transversally-orientated areas and longitudinally-orientatedareas.

The invention is also directed at an absorbent article comprising theabsorbent core and a process for making the absorbent core.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of an absorbent core according to the inventionwith some of the top side of core wrap partially removed;

FIG. 2 is a top view of an alternative absorbent core with twochannel-forming areas within the pattern of absorbent material areas;

FIG. 3 is an alternative absorbent core also with two channel-formingareas wherein some of the longitudinally-orientated areas are curved;

FIG. 4 is a transversal cross-sectional view of the absorbent core ofFIG. 2, with some glue layers highlighted.

FIG. 5 is a longitudinal cross-sectional view of the absorbent core ofFIG. 2, with some glue layers highlighted.

FIG. 6 shows a schematic diagram of an exemplary apparatus for makingthe core.

FIG. 7 is a close-up schematic diagram of the lay-on drum and theprinting roll of FIG. 6.

FIG. 8 shows an example of absorbent article in the form of a tapeddiaper comprising the absorbent core of FIG. 2.

FIG. 9 shows a transversal cross-section of the absorbent article ofFIG. 8.

FIG. 10 shows the transversal cross-section of FIG. 8 after theabsorbent core has absorbed a fluid and channels have been formed in thecore.

DETAILED DESCRIPTION OF THE INVENTION Introduction

As used herein, the terms “comprise(s)” and “comprising” are open-ended;each specifies the presence of the feature that follows, e.g. acomponent, but does not preclude the presence of other features, e.g.elements, steps, components known in the art or disclosed herein. Theseterms based on the verb “comprise” should be read as encompassing thenarrower terms “consisting essentially of” which excludes any element,step or ingredient not mentioned which materially affect the way thefeature performs its function, and the term “consisting of” whichexcludes any element, step, or ingredient not specified. Any preferredor exemplary embodiments described below are not limiting the scope ofthe claims, unless specifically indicated to do so. The words“typically”, “normally”, “preferably”, “advantageously”, “in particular”and the likes also qualify features which are not intended to limit thescope of the claims unless specifically indicated to do so.

Unless indicated otherwise, the description and claims refer to theabsorbent core and article before use (i.e. dry, and not loaded with afluid) and conditioned at least 24 hours at 21° C.+/−2° C. and 50+/−20%Relative Humidity (RH).

General Description of the Absorbent Core 28

As used herein, the term “absorbent core” refers to an individualcomponent, which is placed, or is intended to be placed, within anabsorbent article and which comprises an absorbent material enclosed ina core wrap. As used herein, the term “absorbent core” does not includethe topsheet, the backsheet and (if present) an acquisition-distributionlayer or multilayer system, which is not integral part of the absorbentcore, in particular which is not placed within the core wrap. Theabsorbent core is typically the component of an absorbent article thathas the most absorbent capacity of all the components of the absorbentarticle and which comprises all, or at least the majority of,superabsorbent polymer (SAP). The core may consist essentially of, orconsist of, the core wrap, the absorbent material and adhesives. Theterms “absorbent core” and “core” are herein used interchangeably.

The absorbent cores of the invention are substantially planar. Bysubstantially planar, it is meant that the absorbent core can be laidflat on a surface. The absorbent cores may also be typically thin andconformable, so that they can also be laid on a curved surface forexample a drum during the making process, or stored and handled as acontinuous roll of stock material before being converted into anabsorbent article.

For ease of discussion, the exemplarily absorbent cores of FIGS. 1-3 arerepresented in a flat state. The absorbent core is relatively thinrelative to its other dimensions in the transversal direction (x) andthe longitudinal direction (y). Unless otherwise indicated, dimensionsand areas disclosed herein apply to the core in this flat-outconfiguration. The same applies to an absorbent article, as exemplarilyrepresented in FIG. 8 by a taped diaper, in which the core isintegrated. For absorbent articles which are presented to the user in analready closed form such as training pants or adult incontinence pants,the side seams of these articles may be cut open to lay the article flatif desired. For ease of discussion, the absorbent cores and articles ofthe invention will be discussed with reference to the Figures and thenumerals referred to in these Figures; however these are not intended tolimit the scope of the claims unless specifically indicated.

The absorbent cores 28 illustrated comprise a front edge 280, a backedge 282 and two longitudinal side edges 284, 286 joining the front edgeand the back edge. The front edge of the core is the edge intended to beplaced towards the front edge of the absorbent article in which the coreis or will be integrated. Typically the absorbent material of the coremay be advantageously distributed in somewhat higher amount towards thefront edge than towards the back edge as more absorbency is typicallyrequired towards the front half of the article. Typically the front andback edges 280, 282 of the core may be shorter than the side edges 284,286 of the core. The absorbent core also comprises a top side 288 and abottom side 290. The top side of the core is placed or intended to beplaced towards the topsheet 24 of the article and the bottom side is theside placed or intended to be placed towards the backsheet 25 in thefinished article. The top side of the core wrap is typically morehydrophilic than the bottom side.

The absorbent core may be notionally divided by a longitudinal axis 80extending from the front edge 280 to the back edge 282 and dividing thecore in two substantially symmetrical halves relative to this axis, whenviewing the core in the plane formed by the longitudinal and transversaldirection (x, y). The length L of the core is measured from the frontedge 280 in direction of the back edge 282 along the longitudinal axis80, including the region of the core wrap which does not enclose theabsorbent material, in particular at the front and back end seals whenpresent. The width W of the core is the maximum dimension of the corewrap measured along the transversal direction (x). The outline of theabsorbent core defined by the core wrap can typically be generallyrectangular. The width W and length L of the core may vary depending onthe intended usage. For baby care applications such as diapers andinfant training pants for example, the width of the core may typicallyranges from 4 cm to 21 cm and the length from 10 cm to 62 cm dependingon the size and capacity desired. Adult incontinence products may haveeven higher dimensions.

The transversal axis 90 of the core (herein also referred to as “crotchline”), is defined as the virtual line perpendicular to the longitudinalaxis and passing through the crotch point C of the core. The crotchpoint C is defined as the point of the absorbent core placed at adistance of 0.45 of L from the front edge 280 of the absorbent core, asillustrated on FIG. 1. The absorbent core 28 may also be notionallydivided in three regions, a front region 81 placed towards the frontedge 280, a middle region (also called middle region) 82 and a backregion 83 towards the back edge 282 of the core. These three regions areof equal length in the longitudinal direction as measured on thelongitudinal axis 80, equal to a third of L (L/3).

The absorbent core comprises an absorbent material 60 encompassed withinthe core wrap. The absorbent material is substantially free of cellulosefibers, meaning it comprises at least less than 20% by weight ofcellulose fibers relative to the total weight of absorbent material, inparticular less than 10%, or less than 5% and down to 0% by weight. Theabsorbent material may typically comprise a high proportion ofsuperabsorbent polymer (herein abbreviated as “SAP”). The SAP contentrepresents at least 80% and up to 100% by weight of the absorbentmaterial contained in the core wrap. The SAP may in particular be inparticulate forms (SAP particles). The absorbent core may thus berelatively thin, in particular thinner than conventional corescomprising cellulosic fibers. In particular, the caliper of the core(before use) as measured at the crotch point (C) or at any other pointsof the surface of the core according to the Core Caliper Test asdescribed herein may be from 0.25 mm to 5.0 mm, in particular from 0.5mm to 4.0 mm.

The core wrap may, as shown in the Figures, comprise a first substrate16 and a second substrate 16′, but it is not excluded that the core wrapis made of a single substrate. When two substrates are used, the corewrap may have a C-wrap seal 284′, 286′ along each longitudinal sideedges 284, 286 of the core. The core wrap is not considered as absorbentmaterial for the purpose of calculating the percentage of SAP in theabsorbent core.

The basis weight (amount deposited per unit of surface) of the SAP mayalso be varied to create a macroscopic profiled distribution ofabsorbent material in the longitudinal direction (y) and/or thetransversal direction (x). There may be in particular more absorbentmaterial in the middle region than in the front region and/or the backregion. There maybe also more absorbent material in the front regionthan in the back region.

The absorbent material 60 forms a pattern of discrete absorbent materialareas, as seen from the top of the core in the plane of the core (asrepresented in FIG. 1 for example). The discrete absorbent materialareas are separated from one another by substantially absorbentmaterial-free areas. The pattern comprises transversally-orientatedareas 752 and longitudinally-orientated areas 754. The different shapesof the areas allow them to provide different functions. When theabsorbent material swells in presence of a moderate quantity of fluid,void spaces between the top side and bottom side of core wrap are formedalong the areas substantially free of absorbent material separating theabsorbent material areas. These void spaces have low resistance to thefluid flow and can lead an insulting fluid away from the point of insultin the direction of their orientation. The void spaces between thetransversally-orientated areas and/or longitudinally-orientated areascan also create bending lines along the respective direction of theseareas, thus providing improved flexibility of the core in these areas.As the absorbent material absorbs more fluid, the absorbent materialareas may further swell and at least some of the areas merge together.

In some embodiments, as shown on FIGS. 2 and 3 for example, theabsorbent core may further comprise at least one, in particular at leasttwo longitudinally extending channel-forming areas 26, which aresubstantially free of absorbent material and through which the top sideof the core wrap is attached to the bottom side of the core wrap. Thesechannel-forming areas forms three-dimensional channels 26′ when theabsorbent material adjacent the channel-forming areas absorbs a fluidand swells. As will be detailed below, the core wrap bond 27 between thetop side and bottom side of the core wrap in these area may be at leastpartially formed by an auxiliary glue 72 applied directly to the innersurface of at least one of the substrate. The absorbent core may furthercomprise a fibrous thermoplastic adhesive 74. Such a fibrousthermoplastic adhesive may help to further immobilize the absorbentmaterial and/or help forming the bond 27 within the channel-formingmaterial free zones 26 of the absorbent core. The absorbent core mayadvantageously provide a sufficient immobilization of the absorbentmaterial in dry and wet state. The absorbent core advantageouslyachieves an SAP loss of no more than about 70%, 60%, 50%, 40%, 30%, 20%,or 10% according to the Wet Immobilization Test described inUS2010/0051166A1.

The absorbent cores of the invention will typically be used in anabsorbent article, for example a taped diaper as shown on FIG. 8 in aflat-out state. The longitudinal axis 80 of the core may be thencontiguous with the longitudinal axis 80′ of the article. The articlemay comprise a liquid permeable topsheet 24 and a liquid impermeablebacksheet 25 with the absorbent core 28 positioned between the topsheetand the backsheet.

The absorbent cores and articles of the invention will be furthergenerally described below and by way of illustration with theembodiments exemplarily shown in the Figures, which are not consideredlimiting the scope of the invention unless indicated otherwise.

Core Wrap 16, 16′

The core wrap encloses the absorbent material. Typically and as shown inthe Figures, the core wrap may be formed by a first substrate 16 and asecond substrate 16′. Other core wrap constructions are not excluded,for example it is also possible to use a single substrate to form a corewrap, as in a parcel wrap for example. The first substrate and secondsubstrate may be attached to each other along at least some andtypically all the edges of the absorbent core, by forming transversaland longitudinal seals.

The substrates may be formed by any materials suitable for receiving andcontaining the absorbent material. Typical substrate materials used arein particular paper, tissues, films, wovens or nonwovens, or laminate ofany of these. The core wrap may in particular be formed by a nonwovenweb, such as a carded nonwoven, spunbond nonwoven (“S”) or meltblownnonwoven (“M”), and laminates of any of these. For example spunmeltpolypropylene nonwovens are suitable, in particular those having alaminate web SMS, or SMMS, or SSMMS, structure, and having a basisweight range of about 5 gsm to 15 gsm. Suitable materials are forexample disclosed in U.S. Pat. No. 7,744,576, US2011/0268932A1,US2011/0319848A1 and US2011/0250413A1. Nonwoven materials provided fromsynthetic fibers may be used, such as PE, PET and in particular PP.

As used herein, the terms “nonwoven layer” or “nonwoven web” generallymeans a manufactured sheet, web or batt of directionally or randomlyorientated fibers, bonded by friction, and/or cohesion and/or adhesion,excluding paper and products which are woven, knitted, tufted,stitch-bonded incorporating binding yarns or filaments, or felted bywet-milling, whether or not additionally needled. The fibers may be ofnatural or synthetic origin and may be staple or continuous filaments orbe formed in situ. Commercially available fibers have diameters rangingfrom less than about 0.001 mm to more than about 0.2 mm and they come inseveral different forms such as short fibers (known as staple, orchopped), continuous single fibers (filaments or monofilaments),untwisted bundles of continuous filaments (tow), and twisted bundles ofcontinuous filaments (yam). Nonwoven webs can be formed by manyprocesses such as meltblowing, spunbonding, solvent spinning,electrospinning, carding and airlaying. The basis weight of nonwovenwebs is usually expressed in grams per square meter (g/m² or gsm).

As represented in the Figures, the first substrate 16 may substantiallyform the whole of the top surface 288 of the core wrap and the secondsubstrate 16′ substantially the whole of the bottom surface 290 of thecore wrap, but it is not excluded that this may be the other way round.The expression “substrate substantially forming the whole of thesurface” also includes that case where outwardly extending flaps (seeC-wrap construction below) of the other substrate form part of thesurface considered. The substrates are typically substantially planar inthe same plane as the absorbent core, and each comprises an externalsurface and an internal surface. The internal surface is orientatedtowards the absorbent material and the external surface is the oppositesurface. At least one of the substrate may comprise at least one, andadvantageously two, outwardly extending flaps, which are folded aroundthe front, back or side edges of the absorbent core and then attached tothe external surface of the other substrate to form a so-called C-wrapseal. This is exemplarily represented in FIG. 4, where the firstsubstrate 16 comprises two longitudinally-extending side flaps which arefolded over the side edges 284, 286 and then attached to the externalsurface of the second substrate 16′. The flaps may be attached to theouter surface of the second substrate for example by using an adhesiveseal 284′, 286′ to form a C-wrap seal. One or two continuous orsemi-continuous lines of glue may be typically applied along the lengthof the flaps to bond the inner surface of the flaps to the externalsurface of the other substrate.

As exemplarily represented in FIG. 4, the cores may also compriseso-called sandwich seals 280′, 282′ where the two substrates are bondedto each other in face-to-face relationship with the inner surface ofeach substrate bonded to the inner surface of the other substrate. Thesesandwich seals can for example be formed using a hotmelt glue applied ina series of stripes in a direction perpendicular to the edge over alength of ca. 1 cm for example on the front edge 280 and back edge 282.Thus the core wrap may be sealed with a C-wrap along each of thelongitudinal side edges and a sandwich seal along each of the front andend sides.

The substrates may typically be commercially supplied as rolls ofmaterial of several hundred meters of length. Each roll is thenintegrated in the converting line and unrolled at high speed while theauxiliary adhesive, the absorbent material and the fibrous thermoplasticadhesive layer if present are deposited or applied on the substrate andthen further converted into an absorbent core when a core wrap enclosingthe absorbent material is formed by the second substrate. Typically themachine direction (MD) of the converting line may correspond to thelongitudinal direction (y) of the substrate/core and the cross-machinedirection (CD) to the transversal direction (x) of the substrate/core.The substrates may be cut along the front and back edges of the core280, 282 to individualize the core. This will be further exemplarilydiscussed in the process section further below.

Absorbent Material 60

The absorbent material comprises a high relative amount ofsuperabsorbent polymer (herein referred to as “SAP”). The SAP useful inthe present invention includes a variety of water-insoluble, butwater-swellable polymers capable of absorbing large quantities offluids. The absorbent material may comprise at least 80%, in particularat least 85%, 90%, 95% and up to 100%, of superabsorbent polymer byweight of the absorbent material. The absorbent material may thusadvantageously consist or consist essentially of SAP. The SAP may betypically in particulate forms (superabsorbent polymer particles), butit not excluded that other form of SAP may be used such as asuperabsorbent polymer foam for example.

The term “superabsorbent polymer” refers herein to absorbent materials,which may be crosslinked polymeric materials, and that can absorb atleast 10 times their weight of an aqueous 0.9% saline solution asmeasured using the Centrifuge Retention Capacity (CRC) test (EDANAmethod WSP 241.2-05E). The SAP may in particular have a CRC value ofmore than 20 g/g, or more than 24 g/g, or of from 20 to 50 g/g, or from25 to 40 g/g.

The superabsorbent polymers may be in particulate form so as to beflowable in the dry state and thus easily deposited on the substrate.Typical particulate absorbent polymer materials are made ofpoly(meth)acrylic acid polymers. However, starch-based particulateabsorbent polymer materials may also be used, as well polyacrylamidecopolymer, ethylene maleic anhydride copolymer, crosslinkedcarboxymethylcellulose, polyvinyl alcohol copolymers, crosslinkedpolyethylene oxide, and starch grafted copolymer of polyacrylonitrile.The superabsorbent polymers may be polyacrylates and polyacrylic acidpolymers that are internally and/or surface crosslinked. Suitablematerials are described in WO 07/047598, WO 07/046052, WO 2009/155265and WO 2009/155264. Suitable superabsorbent polymer particles may alsobe obtained by current as described in WO 2006/083584. Thesuperabsorbent polymers are preferably internally cross-linked, i.e. thepolymerization is carried out in the presence of compounds having two ormore polymerizable groups which can be free-radically copolymerized intothe polymer network. In some embodiments, the SAP are formed frompolyacrylic acid polymers/polyacrylate polymers, for example having aneutralization degree of from 60% to 90%, or about 75%, having forexample sodium counter ions.

The SAP particles may be relatively small (under 1 mm in their longestdimension) in their dry state and may be roughly circular in shape, butgranules, fibers, flakes, spheres, powders, platelets and other shapesand forms are also known to persons skilled in the art. Typically, theSAP may be in the form of spherical-like particles. In contrast tofibers, “spherical-like particles” have a longest and a smallestdimension with a particulate ratio of longest to smallest particledimension in the range of 1-5, where a value of 1 would equate aperfectly spherical particle and 5 would allow for some deviation fromsuch a spherical particle. The superabsorbent polymer particles may havea particle size of less than 850 μm, or from 50 to 850 μm, preferablyfrom 100 to 710 μm, more preferably from 150 to 650 μm, as measuredaccording to EDANA method WSP 220.2-05. SAP having a relatively lowparticle size help to increase the surface area of the absorbentmaterial which is in contact with liquid exudates and therefore supportfast absorption of liquid exudates.

The absorbent core may comprise only one type of SAP, but it is notexcluded that a blend of SAPs may be used. The fluid permeability of asuperabsorbent polymer can be quantified using its Urine PermeabilityMeasurement (UPM) value, as measured in the test disclosed Europeanpatent application EP2,679,209A1. The UPM of the SAP may for example beof at least 10×10⁻⁷ cm³.sec/g, or at least 30×10⁻⁷ cm³.sec/g, or atleast 50×10⁻⁷ cm³.sec/g, or more, e.g. at least 80 or 100×10⁻⁷cm³.sec/g.

Pattern of Absorbent Material Areas

The absorbent material forms a pattern of discrete absorbent materialareas within the core wrap. The pattern is considered as shown in theFIGS. 1-3, i.e. in the plane of the absorbent core, for example as seenfrom the top side of the core. The discrete absorbent material areas areseparated by areas substantially free of absorbent material. By“substantially free” it is meant that minimal amount such as involuntarycontaminations with individual absorbent material particles that mayoccur during the making process are disregarded. The pattern ofabsorbent material comprises transversally-orientated areas 752 andlongitudinally-orientated areas 754, 755, 756, 757. These areas have agenerally elongated shape in the transversal direction or longitudinaldirection respectively and may be in particular straight or curved, orcomprise a straight portion and a curved portion.

By “transversally-orientated”, it is meant that the areas extend atleast 2.5 times more in the transversal direction (as projected on aline parallel to x) than in the longitudinal direction (as projected ona line parallel to y), in particular at least 3 times, or at least 4times, or at least 5 times, or at least 10 times and for example up to50 times, or up to 40 times, or up to 30 times, and thetransversally-orientated areas have a dimension in the transversaldirection (as measured by projection on a line parallel to x) which isat least 20% of the width (W) of the absorbent core. By“longitudinally-orientated” it is meant that the areas extend at least2.5 times more in the longitudinal direction (as projected on a lineparallel to y) than in the transversal direction (as projected on a lineparallel to x), in particular at least 3 times, or at least 4 times, orat least 5 times, or at least 10 times and for example up to 50 times,or up to 40 times, or up to 30 times.

The transversally-orientated areas will now be further discussed. Thetransversally-orientated areas can provide different functions. They cancreate a resistance to fluid progression in the longitudinal directionand guide the fluid transversally over a larger area. As an insultingfluid is typically exuded close to the longitudinal centerline, it maybe beneficial that the insulting fluid be distributed over larger areasof the absorbent core in the transversal direction. Thetransversally-orientated areas may also function as bending lines thatcan improve the flexibility of the core longitudinally. This may beparticularly beneficial when the transversally-orientated areas are inthe back region and/or the front region of the absorbent core, as shownin the Figures. These areas of the core can be especially solicited tobend longitudinally towards the user when integrated in the finishedarticle. The transversally-orientated areas may thus be advantageouslypresent in the middle region and/or the back region of the core. Thetransversally-orientated areas may also be absent from the middleregion.

FIGS. 1-3 show transversally-orientated areas 752 that extend withoutinterruption from a longitudinal side edge 284 of the core to theopposite longitudinal side edge 286. All or at least some of thetransversally-orientated areas 752 may for example have a length (asmeasured as projected on a line parallel to the direction of x) which isat least 20% of the width W of the core, in particular from 25% to 99%,or from 50% to 98%, or from 65% to 95% of the width W. Thetransversally-orientated areas may for example have a dimension asprojected on an axis parallel to the transversal axis which is at least2 cm, in particular which ranges from 3 cm to 20 cm, in particular from4 cm to 16 cm, and from 5 to 12 cm.

The length of the transversally-orientated areas 752 may be the same forall these areas, as shown in the Figures, or some may be of varyinglength, in particular for creating a shaped distribution of theabsorbent material to better fit the anatomy of the wearer. Thetransversally-orientated areas 752 may be substantially straight andparallel to the transversal direction (x). It is however not excludedthat they may also be curvilinear (with a single curve, or wavy orotherwise), or otherwise rectilinear (zigzagging, or straight and tiltedat a small angle relative to the transversal direction (x), at an anglewhich may be at the most 30° relative to the transversal direction (x).

The width of a transversally-orientated area 752 may be constant alongthe whole length of the area, as exemplarily represented in the Figures.It is however not excluded that the width of an area may vary, forexample the area being wider towards the longitudinal centerline 80 thantowards the longitudinal side edges (in that case the average width willbe considered in the following to be the width). The width of eachtransversally-orientated area may also be the same or may vary acrossdifferent transversally-orientated areas. The average width of thetransversally-orientated area 752 may range for example from 4 to 20 mm,in particular 5 to 15 mm and exemplarily 10 mm. The distance between thetransversally-orientated areas may typically be shorter than theirwidth, for example ranging from 0.5 to 6 mm, in particular from 1 to 4mm.

Although not represented, it is not excluded that thetransversally-orientated areas may be interrupted by one or morechannel-forming areas 26. The channel-forming areas 26 will be discussedin more details below, but in summary the top side and the bottom sideof the core wrap in the channel-forming areas are bonded to another withsufficient resilience so that they create three-dimensional channelshaving a depth of at least several mm when the adjacent absorbentmaterial swells after absorbing a fluid. This is to be distinguishedfrom the other absorbent material free areas between the transversallyand longitudinally orientated areas, which are typically not bonded orweakly bonded so that the absorbent material is free to swell withoutconstraints in these areas. For the purpose of the characterization ofthe transversally-orientated areas as indicated above, such as length orwidth, the interruption caused by the channel-forming areas 26 aredisregarded.

In addition to the transversally-orientated areas the absorbent materialpattern of the core also comprises longitudinally-orientated areas. Thelongitudinally-orientated areas can provide multiple functions. They canslow the progression of an insulting fluid in the transversal direction,thus slowing fluid progression towards the side edges of the core aswell as distributing the fluid in the longitudinal direction. Thelongitudinally-orientated areas may be at least partially present in themiddle region of the core to prevent side leakage and encouragedistribution of the fluid towards the front and back of the article. Thelongitudinally-orientated areas may also function as bending lines thatcan improve the flexibility of the core laterally. This may beparticularly useful when the longitudinally-orientated areas are atleast partially in the middle region. The improved lateral flexibilityin this region may provide a more comfortable absorbent article. Thelegs of the wearer may typically push the absorbent core together in themiddle region during movement or in certain position, so that improvingthe flexibility of the core in this region may improve comfort.

The longitudinally-orientated areas may in particular be present atleast on the middle region of the core, and extend though the front orback regions. For example, FIG. 1 shows longitudinally-orientated areas754 present in the middle region 82 and extending into the front region81 and the back region 83. The longitudinally-orientated areas 754 maybe substantially straight and parallel to the longitudinal direction (y)as shown in FIG. 1. They may also be curvilinear (with a single curve,or wavy or otherwise), or otherwise rectilinear (zigzagging, or straightand tilted at a small angle relative to the longitudinal direction (y),at an angle which may be at the most 30° relative to the longitudinaldirection (y), or combining a straight portion and a curvilinearportion.

At least some, or all, of the longitudinally-orientated areas 754 may inparticular have a length (as measured as projected to a line parallel toy) which is from 15% to 99% of the length L of the core, in particularfrom 20% to 90%, or from 30% to 80%, or from 35% to 70% of the length L.At least some of the longitudinally-orientated areas may for examplehave a dimension as projected on an axis parallel to the longitudinalaxis which is at least 2 cm, in particular which ranges from 4 cm to 60cm, in particular from 6 cm to 50 cm, and from 10 cm to 40 cm. Thelength of the longitudinally-orientated areas may be the same for allthese areas, but it is not excluded that the length may vary betweenlongitudinally-orientated areas, for example those towards thelongitudinal centerline 80 being longer than those placed furthertowards the side edges (in that case the average length will beconsidered in the following to be the length).

Likewise, the width of each longitudinally-orientated area may be thesame or these may vary for different longitudinally-orientated areas.The average width may range for example from 4 to 20 mm, in particular 5to 15 mm and exemplarily 10 mm (as measured parallel to the transversaldirection x for areas orientated parallel to y). The separating spacesbetween the longitudinally-orientated areas may typically be shorterthan their width, for example ranging from 0.5 to 6 mm, in particularfrom 1 to 4 mm. Some or all the longitudinally-orientated areas may havea length which is at least 2.5 times their widths, in particular atleast 3 times, or at least 4 times, or at least 5 times, and for exampleup to 20 times, or up to 15 times, or up to 10 times the width.

As for the transversally-orientated areas 752, thelongitudinally-orientated areas may be interrupted by one or morechannel-forming areas. Such interrupted longitudinally-orientated areas755 are for example represented on FIG. 2. For the purpose of thecharacterization of the longitudinally-orientated areas, such as lengthor width, the interruption caused by the channel-forming areas 26 aredisregarded. Thus for example as on FIG. 2, the interruptedlongitudinally-orientated areas 755 are considered to have the samelength as the non-interrupted longitudinally-orientated areas 754 forthe purpose of reporting the length of these areas 755.

As generally indicated before, at least some of thelongitudinally-orientated areas may be curvilinear or comprise acurvilinear portion. This is exemplarily represented on FIG. 3 whereinat least a portion 756 of some of the longitudinally-orientatedabsorbent material areas is concave towards the longitudinal axis. Thecurved area may be a smooth curve, i.e. a curve with a continuouslyturning tangent. The curved area may have a substantially constantradius of curvature along the curved portion. The radius of thecurvature may be at least 1.5 times the width W of the core, inparticular at least 2, 4, 6, 8 or 10 times the width W. The curved areamay be concave towards the longitudinal centerline, whereby thelongitudinal centre of these curved areas is closer to the longitudinalaxis 80 of the core than the end points.

When channel-forming areas 26 are present, the neighboringlongitudinally-orientated areas may be parallel to these channel-formingareas, in particular when the channel-forming areas 26 are concavetowards the longitudinal axis. FIG. 3 for example illustrates anabsorbent core comprising a pair of channel-forming areas 26 that arecurvilinear, wherein the absorbent core further compriseslongitudinally-extending absorbent material areas 754 being curvilinearor having a curvilinear portion 756 which run parallel to thechannel-forming areas internally and externally. “Internally” refers tothe longitudinal side of the channel-forming area 26 closest to thelongitudinal edge 80 and “externally” to the opposite side, i.e. closestto the respective longitudinal side edge 284, 286 of the core. Theinternally flanking absorbent material area and/or the externallyflanking absorbent material area can thus also be concave towards thelongitudinal axis 80, at least along their portion parallel to thechannel-forming areas 26. This combination of longitudinally-extendingcurved absorbent material areas 756 following the shape of thechannel-forming areas internally and/or externally can provide benefitsin terms of fluid handling and improved fit. The absorbent core maycomprise for example from 1 to 10 of such externally flankingcurvilinear longitudinally-orientated areas, for example 3 on each sideas represented on FIG. 3. The internally flanking areas may be formed bytwo discrete internally flanking material areas running parallel to thechannel-forming areas 26 in addition to the externally flanking areas,or alternatively by a curvilinear central absorbent material area 757 asillustrated on FIG. 3.

The absorbent core may thus comprise a longitudinally-orientated centralabsorbent material area which is at least partially contiguous with thelongitudinal axis 80 in the middle region of the core. This centralabsorbent material area may be for example straight as shown on FIG. 2.It may be also curved along the channel-forming areas to form internallyflanking areas which run parallel to the internal side of eachchannel-forming area 26, when present, as illustrated on FIG. 3 forexample. Furthermore, the central absorbent material area may bebranching towards the front edge and/or the back edge of the core. Theremay be for example from 2 to 10 of these branches extending towards thefront edge and/or the back edge of the core, for example three towardsthe front and two towards the back as illustrated in FIG. 3. Thesebranches may help providing better flexibility or absorbency of the corein these areas.

Although not represented, it is not excluded that the pattern ofdiscrete absorbent material areas further comprises dot-shaped areas.The dot-shaped areas, when viewed from above, appear as spots which maybe generally round with regular or rugged contours depending on themaking process. For example, the absorbent material may consists of orcomprise SAP particles which are deposited on an substrate by a SAPprinting process as will be discussed further below, and for which thecontour of the dot-shaped areas will be expected to be ragged orirregular due to the high speed process used. Each dot-shaped area takenin isolation may have a different shape, while on average stillapproximating a disc. It is also not excluded that the dot-shaped areasmay also be somewhat oval, rectangular, square, star-shaped or otherwiseirregularly shaped. However, the longitudinal dimension of a dot-shapedarea as measured projected on a line parallel to (y) may be inparticular no more than twice its transversal dimension as measuredprojected on an line parallel to (x) and vice versa. This means that theratio of the dimensions of the dot-shaped areas in longitudinaldirection and in the transversal direction may in particular range from0.5 to 2.0. The dot-shaped area may be in particular relatively small,so that at least some or all of the dot-areas individually entirely fitwithin a notional circle having a diameter of 15 mm or less, inparticular 12.5 mm or less, or even 10 mm or less. The SAP concentration(i.e. basis weight) may typically be higher towards the center of adot-shaped area and gradually decrease towards its boundary.

The dot-shaped areas may be present in any regions of the absorbentcore, and in particular in regions comprising a relatively low basisweight of AGM, such as in the back region 83 of the core. The dot-shapedareas can provide different functions. The dot-shaped areas candistribute an insulting fluid across a wider region, in the transversaland longitudinal directions, thus maximizing the use of the SAP in theregion of the dot-shaped areas, even when the SAP is present at lowbasis weight as is typically the case in the back of the core 83. Afurther benefit of the dot-shaped areas is that they can form athree-dimensional pattern of bumps and recesses when wet. These recessescan serve as receptacles for pasty or runny excrements, which are commonfor small babies. All or at least some of dot-shaped areas may thus beadvantageously present in the back region 83 of the absorbent core tohelp managing pasty or runny excrements.

Typically the absorbent material pattern will be defined and can bepredicted from the making process used for depositing the absorbentmaterial onto the substrate. A SAP printing process for example will usea well-defined printing cylinder and lay-on drum receptacle from whichan expected pattern can be directly deduced. Even if the process usedfor making the cores is not known, the substrates used for the core wrapare usually very thin and at least partially transparent so that theabsorbent material pattern can also be typically discerned with thenaked eye. If for any reasons the core wrap was not transparent enough,other investigative techniques such as X-raying will show the patternwithin the core wrap.

Channel-Forming Area(s) 26 and Channel(s) 26′

The absorbent core may comprise at least one channel-forming area, inparticular at least a pair of generally longitudinally orientatedchannel-forming areas, as exemplarily illustrated in FIGS. 2-3 whichshows two such channel-forming areas 26. In the following the pluralform will be used but it also includes the possibility that there isonly one such channel-forming area. The channel-forming areas 26 areareas of the core which are substantially free of absorbent material andthrough which the top side of core wrap is attached to the bottom sideof the core wrap by a core wrap bond 27. This core wrap bond issufficiently strong so that three-dimensional channels 26′ are formedwhen the absorbent material adjacent the channel-forming areas absorbs afluid and swells. This is for example illustrated in FIGS. 9-10 showingan absorbent article in dry and respectively wet state.

The channel-forming areas 26 are substantially free of absorbentmaterial, so that the bond between the top side and bottom side of thecore wrap can be easily formed, for example by gluing. By “substantiallyfree of absorbent material” it is meant that there can be practically noabsorbent material in these areas 26. Minimal amount such as involuntarycontaminations with absorbent material particles that may occur duringthe making process are disregarded as absorbent material. Thechannel-forming areas 26 are advantageously substantially surrounded bythe absorbent material, when considering the plane of the core Inparticular the channel-forming areas 26 do not extend to any of theedges of the core to reduce the risk of side leakage. Typically, thesmallest distance between a channel-forming area and the closest edge ofthe core may be at least 10 mm.

Within the channel-forming areas, the top side 16 of the core wrap isattached to the bottom side 16′ of the core wrap by a core wrap bond 27as illustrated FIG. 4. It should be understood that FIG. 4 is not madeto scale, as a typical absorbent core is several times thinner as isrepresented in relation to its other dimensions. As illustrated in FIGS.9 and 10 for a complete absorbent article, when the absorbent material60 swells upon absorbing a fluid, the core wrap bonds 27 remain at leastinitially attached in the substantially material free areas 26. Theabsorbent material 60 having swollen in the rest of the core, the corewrap forms channels 26′, i.e. elongated depressions, along the core wrapbond 27. These channels 26′ are three-dimensional and can serve todistribute an insulting fluid along their length to a wider area of thecore. They may provide a quicker fluid acquisition speed and a betterutilization of the absorbent capacity of the core. The channels 26′ canalso provide a deformation of an overlying layer such as a fibrous layer54 and provide corresponding ditches 29 in the overlying layer. Theabsorbent core may comprise other areas substantially free of absorbentmaterial, such as the spaces between the absorbent material areas, butwithout a core wrap bond, these non-bonded areas will typically not formdurable three-dimensional channels.

The core wrap bond 27 may be continuous along each channel-forming area26 but it may also be discontinuous (intermittent) such as formed byseries of point bonds. When present, auxiliary glue 72 may at leastpartially help forming the bond 27. Typically, some pressure can beapplied on the substrates in the areas 26 so that the auxiliary gluebetter forms the bonds between the substrates. Of course it is notexcluded that the core wrap bond 27 is made via other known attachmentmeans, such as pressure bonding, ultrasonic bonding or heat bonding orcombination thereof. If an auxiliary glue 72 is applied on the innersurface of any of the substrates 16, 16′ as a series oflongitudinally-oriented continuous slots, the width and frequency ofthese slots may advantageously be such that at least one slot ofauxiliary glue is present at any level of the channel in thelongitudinal direction. For example, the slots may be 1 mm wide with a 1mm distance between each slot, and the absorbent material free areasforming the channel-forming areas have a width of about 8 mm. In thisexample, 4 slots of auxiliary glue will be present on average in each ofthe areas 26.

The following examples of the shape and size of the channel-formingareas 26 are not limiting. In general, the core wrap bond 27 may havethe same outline but be slightly smaller than the absorbent materialfree areas 26 due to the tolerance required in some manufacturingprocess. The channel-forming areas 26 may be present within the middleregion 82 of the core, in particular at least at the same longitudinallevel as the crotch point C. The absorbent core may also comprise morethan two channel-forming areas, for example at least 3, or at least 4 orat least 5 or at least 6. The channel-forming areas may comprise one ormore pairs of areas symmetrically arranged relative to the longitudinalaxis 80. Shorter area(s) substantially free of absorbent material mayalso be present, for example in the back region or the front region ofthe core, as seen for example in the Figures of WO2012/170778.

The channel-forming areas 26 (and in the following likewise the corewrap bond 27) may be longitudinally-orientated, which means that eachchannel-forming area extends at least as 2.5 times as much in thelongitudinal direction (y) than in the transversal direction (x), andtypically at least 3 times as much in the longitudinal direction than inthe transverse direction (as measured after projection on the respectiveaxis). The channel-forming areas 26 may have a length L′ projected onthe longitudinal axis 80 of the core that is at least 10% of the lengthL of the absorbent core, in particular from 20% to 80%. It may beadvantageous that at least some or all of the channel-forming areas 26are not transversely-orientated. The channel-forming areas may besubstantially free of absorbent material along at least part of theirlength across a width Wc which is at least 2 mm, or at least 3 mm or atleast 4 mm, up to for example 20 mm, or 16 mm or 12 mm. The width Wc ofthe areas substantially free of absorbent material may be constantthrough substantially its whole length or may vary along the length ofthe channel-forming areas.

The channel-forming areas 26 may be completely orientated longitudinallyand parallel to the longitudinal axis but may also be curved or straightwith an angle relative to the longitudinal axis 80. In particular someor all these areas, in particular these areas present in the middleregion, may be concave towards the longitudinal axis 80, as for examplerepresented in the Figures for the pair of channels 26. Thechannel-forming areas may be or comprise a smooth curve, i.e. a curvewith a continuously turning tangent. The curve may have a substantiallyconstant radius of curvature along the curved portion. The radius of thecurvature may be at least 1.5 times the width W of the core, inparticular at least 2, 4, 6, 8 or 10 times the width W. It is howevernot excluded that the curve may have a more complicated shape, forexample comprising several inflexion points such as a wave or having avarying radius of curvature along the curve. When one or moresymmetrical pairs of channel-forming areas are present as shown in thefigures, the smallest distance or gap between the pair may be forexample at least 5 mm, or at least 10 mm, or at least 16 mm.

Although not represented in the Figures, the channel-forming areas mayalso be at least in part convex, i.e. bending towards the closestlongitudinal side edge. This may be advantageous if a stiffer absorbentcore is desired, for example for core used in training pant where it maybe desired that the wearer as a feeling that he wears an absorbentarticle and thus improving the potty training process. It is also notexcluded that the curved longitudinally-extending channel-forming areasmay have a portion which is straight, in particular parallel to thelongitudinal axis or under an angle of (e.g. from 5°) up to 30°, or forexample up to 20°, or up to 10° with a line parallel to the longitudinalaxis. The channel-forming areas may also be branched. A channel-formingarea may or may be present that coincides with the longitudinal axis 80of the core.

Three-dimensional channels 26′ form when the absorbent material adjacentthe channel-forming areas 26 absorbs a fluid, typically urine, andswells. The thickness of the core 28 when dry, as represented in all theFigures, including FIG. 9, is exaggerated to clearly show thechannel-forming area. As the core absorbs more liquid, the depressionswithin the absorbent core formed by core wrap bond 27 between the twosubstrates will become deeper and apparent to the eye and the touch. Itis possible to create a sufficiently strong core wrap bond combined witha relatively low amount of SAP and/or a relatively extensible substratematerial so that the channels remain permanent until complete saturationof the absorbent material. On the other hand, the core wrap bonds may insome cases also restrict the swelling of the absorbent material when thecore is substantially loaded.

The core wrap bond 27 may also be designed to gradually open in acontrolled manner when exposed to a large amount of fluid. The bonds maythus remain substantially intact at least during a first phase as theabsorbent material absorbs a moderate quantity of fluid, as shown onFIG. 10. In a second phase the core wrap bonds 27 in the channels canstart opening to provide more space for the absorbent material to swellwhile keeping most of the benefits of the channels such as increasedflexibility of the core in transversal direction and fluid management.In a third phase, corresponding to a very high saturation of theabsorbent core, a more substantial part of the channel bonds can open toprovide even more space for the swelling absorbent material to expand.The strength of core wrap bond 27 within the channels can be controlledfor example by varying the amount and nature of the glue used for theattaching the two sides of the core wrap, the pressure used to make thecore wrap bond and/or the distribution of the absorbent material, asmore absorbent material will usually causes more swelling and will putmore pressure on the bond. The extensibility of the material of the corewrap may also play a role.

Auxiliary Glue 72

The absorbent core 28 may comprise an auxiliary glue 72 applied on theinner surface of the top side and/or the bottom side of the core wrap.The auxiliary glue may be applied directly over the substrate on whichthe absorbent material is deposited, thus helping to at least partiallyimmobilize the absorbent material. The auxiliary glue may also at leastpartially form the core wrap bond 27 of the channel-forming areas. Theauxiliary glue 72 may also be useful to improve the adhesion of thefibrous thermoplastic material 74, when present, to the substrate.

The auxiliary glue 72 may comprise or consist of any kind ofthermoplastic hot-melt adhesives used in the field of absorbent coremaking Such an adhesive generally includes one or more polymers toprovide cohesive strength (e.g., aliphatic polyolefins such asethylene-propylene copolymers, polyetheramides, polyetheresters, andcombinations thereof; ethylene vinyl acetate copolymers;styrene-butadiene or styrene-isoprene block copolymers; etc.), a resinor analogous material (sometimes called a tackifier) to provide adhesivestrength (e.g., hydrocarbons distilled from petroleum distillates;rosins and/or rosin esters; terpenes derived, for example, from wood orcitrus, etc.); and optional waxes, plasticizers or other materials tomodify viscosity (e.g., mineral oil, polybutene, paraffin oils, esteroils, and the like), and/or other additives including, but not limitedto, antioxidants or other stabilizers. Exemplary suitable commercialadhesives are available from Fuller under reference number 1286 or 1358.Further information about hotmelt adhesive chemistry is discussed belowfibrous thermoplastic adhesive layer 74.

The auxiliary glue 72 can be applied by any adhesive applicator known inthe field, in particular bead, slot or spray nozzles. The auxiliary gluemay be in principle applied as a continuous film on the whole of theauxiliary glue application area, however this may unduly increase theusage of adhesive material. Typically the adhesive will thus be applieddiscontinuously to maximize the area covered with a lower amount ofadhesive. The auxiliary glue may thus be applied as a relatively widecurtain of adhesive using as a spray nozzle. The auxiliary glue may alsobe applied discontinuously as a series of discrete application zoneswithin the application area. For example, the auxiliary glue can beapplied using a slot coating process as a pattern comprising a pluralityof spaced-apart slots which may each extend in the longitudinaldirection. The slots may for example have a width of from 0.5 mm to 3mm, and/or have a lateral spacing there-between of from 0.5 mm to 4 mm.The slots 72 may all be of equal length but may also have varyinglength. For example if the absorbent material was also profiledlaterally with more material towards the longitudinal centerline of thesubstrate, it may be beneficial to have longer or wider slots towardsthe center of the substrate. Each slot may be applied continuously inthe longitudinal direction. The slots may all have the same length ormay have different lengths, in case more SAP immobilization wasrequested in some areas. The auxiliary glue 72 may for example beapplied at a basis weight in the range from 0.5 gsm to 10 gsm, inparticular from 1 gsm to 5 gsm, for example 1 or 2 gsm (including thesurface of the spaces between the glue application areas). The basisweight may also vary locally within the auxiliary glue application area.

Microfiber Glue 74

The absorbent core 28 may also comprise a fibrous thermoplastic adhesivematerial 74, also known as microfiber glue, to help immobilizing theabsorbent material 60 within the core wrap. The fibrous thermoplasticadhesive material 74 may be applied, typically by spraying, over theabsorbent material areas after it has been deposited on its substrateduring the core making process. The fibrous thermoplastic adhesivematerial 74 contacts the absorbent material 60 and the substrate layer16 or 16′ in the spaces between the absorbent material areas. Thisimparts an essentially three-dimensional net-like structure to thefibrous layer of thermoplastic adhesive material, which in itself isessentially a two-dimensional structure of relatively small thickness,as compared to the dimension in length and width directions. Thereby,the fibrous thermoplastic adhesive material may provide cavities tocover the absorbent material, and thereby immobilizes this absorbentmaterial. The fibrous adhesive may be for example sprayed on anabsorbent layer.

The thermoplastic adhesive used for the fibrous layer preferably haselastomeric properties, such that the web formed by the fibers on theSAP layer is able to be stretched as the SAP swell. Exemplaryelastomeric, hotmelt adhesives include thermoplastic elastomers such asethylene vinyl acetates, polyurethanes, polyolefin blends of a hardcomponent (generally a crystalline polyolefin such as polypropylene orpolyethylene) and a Soft component (such as ethylene-propylene rubber);copolyesters such as poly(ethylene terephthalate-co-ethylene azelate);and thermoplastic elastomeric block copolymers having thermoplastic endblocks and rubbery mid blocks designated as A-B-A block copolymers:mixtures of structurally different homopolymers or copolymers, e.g., amixture of polyethylene or polystyrene with an A-B-A block copolymer;mixtures of a thermoplastic elastomer and a low molecular weight resinmodifier, e.g., a mixture of a styrene-isoprenestyrene block copolymerwith polystyrene; and the elastomeric, hot-melt, pressure-sensitiveadhesives described herein. Elastomeric, hot-melt adhesives of thesetypes are described in more detail in U.S. Pat. No. 4,731,066 (Korpman).

The fibrous thermoplastic adhesive material may typically have amolecular weight (Mw) of more than 10,000 and a glass transitiontemperature (Tg) usually below room temperature or −6° C.<Tg<16° C.Typical concentrations of the polymer in a hotmelt are in the range ofabout 20% to about 40% by weight. The thermoplastic polymers may bewater insensitive. Exemplary polymers are (styrenic) block copolymersincluding A-B-A triblock structures, A-B diblock structures and (A-B)nradial block copolymer structures wherein the A blocks arenon-elastomeric polymer blocks, typically comprising polystyrene, andthe B blocks are unsaturated conjugated diene or (partly) hydrogenatedversions of such. The B block is typically isoprene, butadiene,ethylene/butylene (hydrogenated butadiene), ethylene/propylene(hydrogenated isoprene), and mixtures thereof. Other suitablethermoplastic polymers that may be employed are metallocene polyolefins,which are ethylene polymers prepared using single-site or metallocenecatalysts. Therein, at least one comonomer can be polymerized withethylene to make a copolymer, terpolymer or higher order polymer. Alsoapplicable are amorphous polyolefins or amorphous polyalphaolefins(APAO) which are homopolymers, copolymers or terpolymers of C2 to C8alpha olefins.

The tackifying resin may exemplarily have a Mw below 5,000 and a Tgusually above room temperature, typical concentrations of the resin in ahotmelt are in the range of about 30 to about 60%, and the plasticizerhas a low Mw of typically less than 1,000 and a Tg below roomtemperature, with a typical concentration of about 0 to about 15%.

The thermoplastic adhesive material fibers may exemplarily have anaverage thickness of about 1 to about 50 micrometers or about 1 to about35 micrometers and an average length of about 5 mm to about 50 mm orabout 5 mm to about 30 mm. The auxiliary glue may improve the adhesionof the thermoplastic adhesive material to the substrate. The fibersadhere to each other to form a fibrous layer, which can also bedescribed as a mesh.

Method of Making

The absorbent cores 28 and the absorbent articles 20 of the inventionmay be made by any conventional methods known in the art. In particularthe absorbent cores and articles may be hand-made or industriallyproduced at high speed on a modern converting line. The absorbent coresof the invention can in particular be made industrially by the so-calledSAP printing process using the method generally disclosed inUS2006/024433 (Blessing), US2008/0312617 and US2010/0051166A1 (both toHundorf et al.) and US2014/0027066A1, with some adaptations. Thisprocess will now be discussed herein in more details, being itunderstood that the process described should not be considered limitingfor interpreting the scope of the product claims.

FIG. 6 schematically shows a printing unit for making an absorbent corecorresponding to the core shown on FIG. 2. In this drawing, thesubstrate 16 is fed from the right side to an idler (rotatable supportroll) 118. The auxiliary glue 72 may be applied between a free spanbetween two further idlers 119-120 by an auxiliary glue applicator 136.The auxiliary glue applicator 136 may be a nozzle system which canprovide a relatively thin but wide curtain of thermoplastic adhesivematerial as suggested in WO2008/155699, but may also alternatively andadvantageously comprise a slot coater for applying simultaneouslyseveral slots of auxiliary glue 72 longitudinally along a desired widthof the substrate.

A SAP hopper 142 holds and dispenses a flowable absorbent material 60such as SAP particles (which for simplicity will be designated as SAP inthe following) to the cavities 122 of the printing roll 144. Onepossibility to hold the material in the cavities 122 may be a vacuumapplied to the inner side of the printing roll and symbolized by the −sign on the Figure. The bottom of the cavities may be provided with afine mesh so that the absorbent material is not further drawn within theprinting roll. The vacuum is for example released or inverted justbefore or at the meeting point with the lay-on drum, as symbolized bythe + sign. The SAP is deposited from the printing roll 144 on to thesubstrate 16 at a meeting point where the printing rolls is closest tothe lay-on drum 132. This step will be described in more details belowwith reference to FIG. 7.

A thermoplastic adhesive material applicator 150 may then apply thefibrous thermoplastic adhesive material 74 on the deposited absorbentmaterial. The substrate 16 and the absorbent material deposited thereonmay be directly put in face-to-face relation with a second substrate 16′using a pressure roll 131. The pressure roll 131 can further cooperatewith lay-on drum to form channel-forming areas by applying pressure onthe desired absorbent material-free area of the core. The downstreampressure roll can have a raised pressure pattern substantiallycorresponding to the mating strips, for contacting the substrate in anarea thereof corresponding to a channel (see US20140027066).

The continuous supply of absorbent core may then be further driven pasta rotatable support roll 121 to a sealing unit (not represented). Thecore lateral edges may be sealed longitudinally as a C-wrap in a sealforming guide roller by continuously folding the laterally extendingflaps of one of the substrate. The absorbent cores 28 can then beindividualized by forming the front and back seals and cutting the webof the core material at the required interval. The end seal glue may forexample be applied on any of the first and second substrates beforethese are brought in face to face relationship. The continuous flow ofabsorbent cores can then be integrated into a converting process formaking an absorbent article.

The absorbent material deposition step, or printing step, isschematically illustrated in FIG. 7, which only shows how the printingroll 144 and the lay-on drum 132 cooperate to precisely deposit the SAPonto the substrate. The printing roll 144 comprises on its periphery aplurality of cavities 122 that can be filled with SAP particles. Thecavities 122 have a pre-determined volume so that the amount of SAPfilled is precisely controlled. The cavities may have any kind of shape,for example they may generally have an inverted dome-shape. Thesecavities may be arranged in a series of transversal rows but otherarrangements are possible. The printing roll shown comprises a pair ofareas 21 free of cavities and surrounded by the cavities 122. Theseareas 21 correspond to the absorbent material-free area that will formchannel-forming areas. Of course the printing roll may comprise no, oronly one or more than a pair of these cavity-free areas 21. The areas 21may be flush with the surface of the printing roll or may be raised.

The cavities may be connected to a vacuum (shown by the minus sign “−”in the Figures through a grid (not shown) in the fill area of the drum,typically at the upper region of drum (corresponding ca. to the anglebetween ca. 11 to 3 o'clock in FIG. 7), the vacuum being also present inan absorbent material retention area (ca. 3 to 5 o'clock) to ensure thatthe material does not escape the cavities before being deposited. Whenthe cavities approaches the meeting point, the vacuum is switched offand may be replaced by overpressure (represented by the sign ++ for“high” pressure area between ca. 5 and 7 o'clock) to completely blow theSAP out of the cavities onto the substrate. Another internal printingroll chamber with some overpressure (e.g from 7 to 10 'clock symbolizedby the “+” sign for “low” pressure) may be provided to clean up thecavities from any remaining SAP before these are filled again foranother printing cycle.

The printing-roll 144 comes in close proximity of the lay-on roll 132 ata meeting point so that the SAP can be accurately transferred to thesubstrate 16 supported on the lay-on drum 132. The lay-on drum 132 isgenerally circular and comprises on its periphery at least one andtypically a plurality of receptacles 133, each receptacle beingsubstantially identical to the preceding and providing a full depositionpattern for one core. A lay-on drum may for example comprise about 4such receptacles 133 for absorbent cores for baby diapers size 4. For agiven size of the drum, more receptacles may be present if the cores tobe made are smaller. The diameter of the printing roll 144 may be asshown smaller than the lay-on drum 132, so that a complete turn of thelay-on drum corresponds to several turns of the printing rolls, e.g. ina relation of 4 to 1 for size 4 absorbent core.

Each receptacle 133 comprises at its surface a pattern oflongitudinally-oriented depressions 138 and transversally-orienteddepressions 138′. These depressions may be designated by their usualterm “air-slots”. The depressions are arranged to provide the pattern ofabsorbent material deposition desired. The receptacle itself maycomprise longitudinally-oriented rods 36 (also called “MD bars”),transversally-orientated rods 36′ (“also called “CD bars”) between whichthe depression 138, 138′ are formed. The depressions 138 are connectedto a vacuum (represented by the double minus sign “−−” in FIGS. 6-7) asthey approach the SAP deposition area at the meeting point. This vacuumhelps maintaining the substrate 16 taut on the lay-on drum. Furthermore,this vacuum somewhat pulls the substrate inwards of the surface of thelay-on drum through the depressions 138. In this way, small undulationsare formed at the surface of the substrate matching the outline of theunderlying depressions. A grid may be present at the bottom of thedepressions. These undulations generally define the shape of thedeposited absorbent material area, as the vacuum will also help suckingand directing the SAP 60 from the print roll 144 at the meeting pointonto the undulations. The vacuum exerted through each depressionscombined by the over-blow pressure on the print roll will bring thedeposited SAP to generally follow the shape of the depressions to formcontinuous areas, and this even if the cavities 122 have another shapesuch as discrete dome-shaped cavities. After passing the meeting point,a lower vacuum may be used to keep the substrate and the SAP in placewhile the microfiber glue is applied (as shown in FIG. 6 but not shownon FIG. 7).

Longitudinally-orientated depressions 138 will generally allowdepositing longitudinally-orientated absorbent material area 754,transversally-orientated depressions 138′ transversally-orientatedabsorbent material area 752. Some of the depressions may have at least acurvilinear portion to provide for curved absorbent material area 756.Generally circular depressions when present will help forming dot-shapedmaterial areas. It should be understood that the process described aboveis not intended to be limiting on the product claims.

The receptacle 133 on the lay-on drum may comprise a pair of matingstrips 31 that corresponds to the cavity-free area 21 on the lay-ondrum. The mating strips 31 may be flush with the surface of the lay-ondrum but may be advantageously slightly raised by a few mm. Such matingstrips/cavity-free areas combinations 21, 31 are exemplarily disclosedin further details in US2012/0312491 (Jackels). The pressure drum 131may have matching strips (not represented) that may also be slightlyraised so that a localized pressure is applied on both substrates 16,16′ at the area corresponding to the raised strips 31, thus providing acore wrap bond 27 and channel-forming areas 26.

In summary, the SAP printing technology exemplarily described aboveallows for high-speed and precise deposition of SAP on a substrate withor without channel-forming areas. It should however be understood thatother processes than those represented can be used to make the claimedabsorbent cores.

General Description of the Absorbent Article 20

An exemplary absorbent article 20 according to the invention in the formof a baby taped diaper 20 is represented in FIGS. 8-10. FIG. 8 is a topplan view of the exemplary diaper 20, in a flat-out state, with portionsof the structure being cut-away to more clearly show the construction ofthe diaper 20. FIG. 9 is transversal cross-sectional view of the diaper20 taken along the transversal centerline 90′ in FIG. 8. This diaper 20is shown for illustration purpose only as the absorbent core may be usedfor other absorbent articles, in particular type of baby diapers ortraining pants.

The absorbent article 20 comprises a liquid permeable topsheet 24, aliquid impermeable backsheet 25 and an absorbent core 28 according tothe invention between the topsheet 24 and the backsheet 25. Theabsorbent article may also comprise further typical components such asan acquisition layer and/or a distribution layer (collectively referredto as acquisition-distribution system “ADS”, designated as 54), andelasticized gasketing cuffs 32 present between topsheet and backsheetand upstanding barrier leg cuffs 34, which will be further detailed inthe following. The Figures also show other typical taped diapercomponents such as a fastening system comprising fastening tabs 42attached towards the back edge 12 of the article and cooperating with alanding zone 44 towards the front edge 10 of the article. The absorbentarticle may also comprise other typical components, which are notrepresented in the Figures, such as a back elastic waist feature, afront elastic waist feature, transverse barrier cuffs, a wetnessindicator that changes appearance when contacted with urine, a lotionapplication, etc.

The absorbent article 20 comprises a front edge 10, a back edge 12, andtwo longitudinally extending side (lateral) edges 13, 14. The front edge10 is the edge of the article which is intended to be placed towards thefront of the user when worn, and the back edge 12 is the opposite edge.The absorbent article may be notionally divided by a longitudinal axis80′ extending from the front edge to the back edge of the article anddividing the article in two substantially symmetrical halves relative tothis axis, when viewing the article from the wearer facing side in aflat out configuration, as exemplarily shown in FIG. 8. This axis 80′may typically be concomitant with the longitudinal axis 80 of the core.If some part of the article is under tension due to elasticizedcomponents, the article may be typically flattened using clamps alongthe periphery of the article and/or a sticky surface, so that thetopsheet and backsheet can be pulled taut so as to be substantiallyflat. Closed articles such as training pant may be cut open along theside seams to apply them on a flat surface. Unless otherwise indicated,dimensions and areas disclosed herein apply to the article in thisflat-out configuration. The article has a length L″ as measured alongthe axis 80′ from the back edge to the front edge. The absorbent article20 can also be notionally divided by a transversal axis 90′ into a frontregion and a back region of equal length measured on the longitudinalaxis, when the article is in such a flat state. This article'stransversal axis 90′ is perpendicular to the longitudinal axis 80′ andplaced at half the length of the article.

The topsheet 24, the backsheet 25, the absorbent core 28 and the otherarticle components may be assembled in a variety of well-knownconfigurations, in particular by gluing and/or heat embossing. Exemplarydiaper assemblies are for example generally described in U.S. Pat. No.3,860,003, U.S. Pat. No. 5,221,274, U.S. Pat. No. 5,554,145, U.S. Pat.No. 5,569,234, U.S. Pat. No. 5,580,411, and U.S. Pat. No. 6,004,306. Theabsorbent article is preferably thin. The article may be advantageouslythin at the intersection of the longitudinal and transversal axes, forexample with a caliper of from 1.0 mm to 8.0 mm, in particular from 1.5mm to 6.0 mm, as measured using the Absorbent Article Caliper Testdescribed below.

These and other components of the article will now be discussed in moredetail. Dimensions and values disclosed herein are not to be understoodas being strictly limited to the exact numerical values recited.Instead, unless otherwise specified, each such dimension is intended tomean both the recited value and a functionally equivalent rangesurrounding that value. For example, a dimension disclosed as “40 mm” isintended to mean “about 40 mm”.

Topsheet 24

The topsheet 24 is the part of the absorbent article 20 that is directlyin contact with the wearer's skin. The topsheet 24 can be joined to thebacksheet 25, the absorbent core 28 and/or any other layers as is knownin the art (as used herein, the term “joined” encompasses configurationswhereby an element is directly secured to another element by affixingthe element directly to the other element, and configurations whereby anelement is indirectly secured to another element by affixing the elementto intermediate member(s) which in turn are affixed to the otherelement). Usually, the topsheet 24 and the backsheet 25 are joineddirectly to each other in some locations (e.g. on or close to theperiphery of the article) and are indirectly joined together in otherlocations by directly joining them to one or more other elements of thearticle 20.

The topsheet 24 is preferably compliant, soft-feeling, andnon-irritating to the wearer's skin. Further, at least a portion of thetopsheet 24 is liquid permeable, permitting liquids to readily penetratethrough its thickness. A suitable topsheet may be manufactured from awide range of materials, such as porous foams, reticulated foams,apertured plastic films, or woven or nonwoven materials of naturalfibers (e.g., wood or cotton fibers), synthetic fibers or filaments(e.g., polyester or polypropylene or bicomponent PE/PP fibers ormixtures thereof), or a combination of natural and synthetic fibers. Ifthe topsheet 24 includes fibers, the fibers may be spunbond, carded,wet-laid, meltblown, hydroentangled, or otherwise processed as is knownin the art, in particular spunbond PP nonwoven. A suitable topsheetcomprising a web of staple-length polypropylene fibers is manufacturedby Veratec, Inc., a Division of International Paper Company, of Walpole,Mass. under the designation P-8.

Suitable formed film topsheets are also described in U.S. Pat. No.3,929,135, U.S. Pat. No. 4,324,246, U.S. Pat. No. 4,342,314, U.S. Pat.No. 4,463,045, and U.S. Pat. No. 5,006,394. Other suitable topsheets maybe made in accordance with U.S. Pat. No. 4,609,518 and U.S. Pat. No.4,629,643. Such formed films are available from The Procter & GambleCompany of Cincinnati, Ohio as “DRI-WEAVE” and from TredegarCorporation, based in Richmond, Va., as “CLIFF-T”.

Any portion of the topsheet may be coated with a lotion as is known inthe art. Examples of suitable lotions include those described in U.S.Pat. No. 5,607,760, U.S. Pat. No. 5,609,587, U.S. Pat. No. 5,643,588,U.S. Pat. No. 5,968,025 and U.S. Pat. No. 6,716,441. The topsheet 24 mayalso include or be treated with antibacterial agents, some examples ofwhich are disclosed in WO 95/24173. Further, the topsheet, the backsheetor any portion of the topsheet or backsheet may be embossed and/or mattefinished to provide a more cloth like appearance.

The topsheet 24 may comprise one or more apertures to ease penetrationof exudates therethrough, such as urine and/or feces (solid, semi-solid,or liquid). The size of at least the primary aperture is important inachieving the desired waste encapsulation performance. If the primaryaperture is too small, the waste may not pass through the aperture,either due to poor alignment of the waste source and the aperturelocation or due to fecal masses having a diameter greater than theaperture. If the aperture is too large, the area of skin that may becontaminated by “rewet” from the article is increased. Typically, thetotal area of the apertures at the surface of a diaper may have an areaof between about 10 cm² and about 50 cm², in particular between about 15cm² and 35 cm².

Examples of apertured topsheet are disclosed in U.S. Pat. No. 6,632,504.WO 2011/163582 also discloses suitable colored topsheet having a basisweight of from 12 to 18 gsm and comprising a plurality of bonded points.Each of the bonded points has a surface area of from 2 mm² to 5 mm² andthe cumulated surface area of the plurality of bonded points is from 10to 25% of the total surface area of the topsheet.

Typical diaper topsheets have a basis weight of from about 10 to about28 gsm, in particular between from about 12 to about 18 gsm but otherbasis weights are possible.

Backsheet 25

The backsheet 25 is generally that portion of the absorbent article 20which forms the majority of the external surface of the article whenworn by the user and prevents the exudates absorbed and containedtherein from soiling articles such as bed sheets and undergarments. Thebottom side 290 of the absorbent core 28 is positioned towards thebacksheet 25. The backsheet 25 is typically impermeable to liquids (e.g.urine). The backsheet 25 may for example be or comprise a thin plasticfilm such as a thermoplastic film having a thickness of about 0.012 mmto about 0.051 mm. Exemplary backsheet films include those manufacturedby Tredegar Corporation, based in Richmond, Va., and sold under thetrade name CPC2 film. Other suitable backsheet materials may includebreathable materials which permit vapors to escape from the article 20while still preventing exudates from passing through the backsheet 25.Exemplary breathable materials may include materials such as woven webs,nonwoven webs, composite materials such as film-coated nonwoven webs,microporous films such as manufactured by Mitsui Toatsu Co., of Japanunder the designation ESPOIR NO and by Tredegar Corporation of Richmond,Va., and sold under the designation EXAIRE, and monolithic films such asmanufactured by Clopay Corporation, Cincinnati, Ohio under the nameHYTREL blend P18-3097. Some breathable composite materials are describedin greater detail in WO 95/16746 (E. I. DuPont), U.S. Pat. No. 5,938,648(LaVon et al.), U.S. Pat. No. 4,681,793 (Linman et al.), U.S. Pat. No.5,865,823 (Curro), U.S. Pat. No. 5,571,096 (Dobrin et al.) and U.S. Pat.No. 6,946,585 (London Brown).

The backsheet 25 may be joined to the topsheet 24, the absorbent core 28or any other element of the diaper 20 by any attachment means known inthe art. Suitable attachment means are described above with respect tomeans for joining the topsheet 24 to other elements of the article 20.For example, the attachment means may include a uniform continuous layerof adhesive, a patterned layer of adhesive, or an array of separatelines, spirals, or spots of adhesive. Suitable attachment meanscomprises an open pattern network of filaments of adhesive as disclosedin U.S. Pat. No. 4,573,986. Other suitable attachment means includeseveral lines of adhesive filaments which are swirled into a spiralpattern, as is illustrated by the apparatus and methods shown in U.S.Pat. No. 3,911,173, U.S. Pat. No. 4,785,996; and U.S. Pat. No.4,842,666. Adhesives which have been found to be satisfactory aremanufactured by H. B. Fuller Company of St. Paul, Minn. and marketed asHL-1620 and HL 1358-XZP. Alternatively, the attachment means maycomprise heat bonds, pressure bonds, ultrasonic bonds, dynamicmechanical bonds, or any other suitable attachment means or combinationsof these attachment means as are known in the art.

Acquisition-Distribution System 54

The absorbent articles of the invention may comprise an acquisitionlayer, a distribution layer, or combination of both (herein collectivelyreferred to as acquisition-distribution system “ADS”, represented as asingle layer 54 in the Figures). The function of the ADS is typically toquickly acquire the fluid and distribute it to the absorbent core in anefficient manner. The ADS may comprise one, two or more layers, whichmay form a unitary layer or remain discrete layers which may be attachedto each other. The ADS may in particular comprises two layers: adistribution layer and an acquisition layer disposed between theabsorbent core and the topsheet, but the invention is not restricted tothis example. Typically, the ADS will not comprise SAP as this may slowthe acquisition and distribution of the fluid. The prior art disclosesmany type of acquisition-distribution system, see for example WO2000/59430 (Daley), WO 95/10996 (Richards), U.S. Pat. No. 5,700,254(McDowall), WO 02/067809 (Graef). The ADS may, although not necessarily,comprise two layers: a distribution layer and an acquisition layer,which will now be exemplified in more detail.

Distribution Layer

The function of a distribution layer is to spread the insulting fluidliquid over a larger surface within the article so that the absorbentcapacity of the core can be more efficiently used. Typically thedistribution layer is made of a nonwoven material based on synthetic orcellulosic fibers and having a relatively low density. The density ofthe distribution layer may vary depending on the compression of thearticle, but may typically range from 0.03 to 0.25 g/cm³, in particularfrom 0.05 to 0.15 g/cm³ measured at 0.30 psi (2.07 kPa). Thedistribution layer 54 may also be a material having a water retentionvalue of from 25 to 60, preferably from 30 to 45, measured as indicatedin the procedure disclosed in U.S. Pat. No. 5,137,537. The distributionlayer 54 may typically have an average basis weight of from 30 to 400g/m², in particular from 100 to 300 g/m².

The distribution layer may for example comprise at least 50% by weightof crosslinked cellulose fibers. The crosslinked cellulosic fibers maybe crimped, twisted, or curled, or a combination thereof includingcrimped, twisted, and curled. This type of material has been used in thepast in disposable diapers as part of an acquisition system, for exampleUS 2008/0312622 A1 (Hundorf). The crosslinked cellulosic fibers providehigher resilience and therefore higher resistance against thecompression in the product packaging or in use conditions, e.g. underbaby weight.

Exemplary chemically crosslinked cellulosic fibers suitable for adistribution layer are disclosed in U.S. Pat. No. 5,549,791, U.S. Pat.No. 5,137,537, WO 95/34329 or US 2007/118087. Exemplary crosslinkingagents include polycarboxylic acids such as citric acid and/orpolyacrylic acids such as acrylic acid and maleic acid copolymers. Forexample, the crosslinked cellulosic fibers may have between about 0.5mole % and about 10.0 mole % of a C2-C9 polycarboxylic acid crosslinkingagent, calculated on a cellulose anhydroglucose molar basis, reactedwith said fibers in an intrafiber ester crosslink bond form. The C2-C9polycarboxylic acid crosslinking agent may be selected from the groupconsisting of:

-   -   aliphatic and alicyclic C2-C9 polycarboxylic acids having at        least three carboxyl groups per molecule; and    -   aliphatic and alicyclic C2-C9 polycarboxylic acids having two        carboxyl groups per molecule and having a carbon-carbon double        bond located alpha, beta to one or both of the carboxyl groups,        wherein one carboxyl group in said C2-C9 polycarboxylic acid        crosslinking agent is separated from a second carboxyl group by        either two or three carbon atoms. The fibers may have in        particular between about 1.5 mole % and about 6.0 mole %        crosslinking agent, calculated on a cellulose anhydroglucose        molar basis, reacted therewith in the form of intrafiber ester        crosslink bonds. The crosslinking agent may be selected from the        group consisting of citric acid, 1, 2, 3, 4 butane        tetracarboxylic acid, and 1, 2, 3 propane tricarboxylic acid, in        particular citric acid.

Polyacrylic acid crosslinking agents may also be selected frompolyacrylic acid homopolymers, copolymers of acrylic acid, and mixturesthereof. The fibers may have between 1.0 weight % and 10.0 weight %,preferably between 3 weight % and 7 weight %, of these crosslinkingagents, calculated on a dry fiber weight basis, reacted therewith in theform of intra-fiber crosslink bonds. The crosslinking agent may be apolyacrylic acid polymer having a molecular weight of from 500 to40,000, preferably from 1,000 to 20,000. The polymeric polyacrylic acidcrosslinking agent may be a copolymer of acrylic acid and maleic acid,in particular wherein the weight ratio of acrylic acid to maleic acid isfrom 10:1 to 1:1, preferably from 5:1 to 1.5:1. An effective amount ofcitric acid may be further mixed with said polymeric polyacrylic acidcrosslinking agent.

The distribution layer comprising crosslinked cellulose fibers maycomprise other fibers, but this layer may advantageously comprise atleast 50%, or 60%, or 70%, or 80%, or 90% or even up to 100%, by weightof the layer, of crosslinked cellulose fibers (including thecrosslinking agents). Examples of such mixed layer of crosslinkedcellulose fibers may comprise about 70% by weight of chemicallycrosslinked cellulose fibers, about 10% by weight polyester (PET)fibers, and about 20% by weight untreated pulp fibers. In anotherexample, the layer of crosslinked cellulose fibers may comprise about70% by weight chemically crosslinked cellulose fibers, about 20% byweight lyocell fibers, and about 10% by weight PET fibers. In anotherexample, the layer may comprise about 68% by weight chemicallycrosslinked cellulose fibers, about 16% by weight untreated pulp fibers,and about 16% by weight PET fibers. In another example, the layer ofcrosslinked cellulose fibers may comprise from about 90-100% by weightchemically crosslinked cellulose fibers.

Acquisition Layer

The absorbent article 20 may comprise an acquisition layer, whosefunction is to quickly acquire the fluid away from the topsheet so as toprovide a good dryness for the wearer. The acquisition layer istypically placed directly under the topsheet. If present, thedistribution layer may be at least partially disposed under theacquisition layer. The acquisition layer may typically be or comprise anon-woven material, for example a SMS or SMMS material, comprising aspunbonded, a melt-blown and a further spunbonded layer or alternativelya carded chemical-bonded nonwoven. The non-woven material may inparticular be latex bonded. Exemplary upper acquisition layers aredisclosed in U.S. Pat. No. 7,786,341. Carded, resin-bonded nonwovens maybe used, in particular where the fibers used are solid round or roundand hollow PET staple fibers (50/50 or 40/60 mix of 6 denier and 9denier fibers). An exemplary binder is a butadiene/styrene latex.Nonwovens have the advantage that they can be manufactured outside theconverting line and stored and used as a roll of material. Furtheruseful nonwovens are described in U.S. Pat. No. 6,645,569 (Cramer etal.), U.S. Pat. No. 6,863,933 (Cramer et al.), U.S. Pat. No. 7,112,621(Rohrbaugh et al.), US 2003/148684 (Cramer et al.) and US 2005/008839(Cramer et al.).

The acquisition layer may be stabilized by a latex binder, for example astyrene-butadiene latex binder (SB latex). Processes for obtaining suchlatices are known, for example, from EP 149880 (Kwok) and US2003/0105190 (Diehl et al.). In certain embodiments, the binder may bepresent in the acquisition layer 52 in excess of about 12%, about 14% orabout 16% by weight. SB latex is available under the trade name GENFLO™3160 (OMNOVA Solutions Inc.; Akron, Ohio).

A further acquisition layer (not shown) may be used in addition to thefirst acquisition layer described above. For example a tissue layer maybe placed between the first acquisition layer and the distributionlayer. The tissue may have enhanced capillarity distribution propertiescompared to the acquisition layer described above. The tissue and thefirst acquisition layer may be of the same size or may be of differentsize, for example the tissue layer may extend further in the back of theabsorbent article than the first acquisition layer. An example of ahydrophilic tissue is a 13 to 15 gsm high wet strength tissue made ofcellulose fibers from supplier Havix.

Fastening System 42, 44

The absorbent article may include a fastening system. The fasteningsystem can be used to provide lateral tensions about the circumferenceof the absorbent article to hold the absorbent article on the wearer.This fastening system is not necessary for training pant article sincethe waist region of these articles is already bonded. The fasteningsystem usually comprises a fastener 42 such as tape tabs, hook and loopfastening components, interlocking fasteners such as tabs & slots,buckles, buttons, snaps, and/or hermaphroditic fastening components,although any other known fastening means are generally acceptable. Alanding zone 44 is normally provided on the front waist region of thearticle for the fastener 42 to be releasably attached. Some exemplarysurface fastening systems are disclosed in U.S. Pat. No. 3,848,594, U.S.Pat. No. 4,662,875, U.S. Pat. No. 4,846,815, U.S. Pat. No. 4,894,060,U.S. Pat. No. 4,946,527, U.S. Pat. No. 5,151,092 and U.S. Pat. No.5,221,274 (Buell). An exemplary interlocking fastening system isdisclosed in U.S. Pat. No. 6,432,098. The fastening system may alsoprovide a means for holding the article in a disposal configuration asdisclosed in U.S. Pat. No. 4,963,140 (Robertson et al.)

The fastening system may also include primary and secondary fasteningsystems, as disclosed in U.S. Pat. No. 4,699,622 to reduce shifting ofoverlapped portions or to improve fit as disclosed in U.S. Pat. No.5,242,436, U.S. Pat. No. 5,499,978, U.S. Pat. No. 5,507,736, and U.S.Pat. No. 5,591,152.

Front and Back Ears 46, 40

The absorbent article may comprise front ears 46 and back ears 40 as isknown in the art. The ears can be integral part of the chassis, forexample formed from the topsheet and/or backsheet as side panel.Alternatively, as represented in FIG. 8, they may be separate elementsattached by gluing and/or heat embossing. The back ears 40 areadvantageously stretchable to facilitate the attachment of the tabs 42on the landing zone 44 and maintain the taped diapers in place aroundthe wearer's waist. The front ears 46 may also be elastic or extensibleto provide a more comfortable and contouring fit by initiallyconformably fitting the absorbent article to the wearer and sustainingthis fit throughout the time of wear well past when absorbent articlehas been loaded with exudates since the elasticized ears allow the sidesof the absorbent article to expand and contract.

Barrier Leg Cuffs 34 and Gasketing Cuffs 32

Absorbent articles such as diapers or training pants may typicallyfurther comprise components that improve the fit of the article aroundthe legs of the wearer, in particular barrier leg cuffs 34 and gasketingcuffs 32. The barrier leg cuffs may be formed by a piece of material,typically a nonwoven, which is partially bonded to the rest of thearticle and can be partially raised away and thus stand up from theplane defined by the topsheet, when the article is pulled flat as shownfor example in FIG. 8. The barrier leg cuffs 34 can provide improvedcontainment of liquids and other body exudates approximately at thejunction of the torso and legs of the wearer. The barrier leg cuffs 34extend at least partially between the front edge and the back edge ofthe absorbent article on opposite sides of the longitudinal axis and areat least present adjacent to the crotch point (C).

The barrier leg cuffs 34 may be delimited by a proximal edge 64 joinedto the rest of the article, typically the topsheet and/or the backsheet,and a free terminal edge 66 intended to contact and form a seal with thewearer's skin. The barrier leg cuffs 34 may be joined at the proximaledge 64 with the chassis of the article by a bond 65 which may be madefor example by adhesive bonding, fusion bonding or combination of knownbonding means. The bond 65 at the proximal edge 64 may be continuous orintermittent.

The barrier leg cuffs 34 can be integral with (i.e. formed from) thetopsheet or the backsheet, or more typically be formed from a separatematerial joined to the rest of the article. Typically the material ofthe barrier leg cuffs may extend through the whole length of the articlebut is “tack bonded” to the topsheet towards the front edge and backedge of the article so that in these sections the barrier leg cuffmaterial remains flush with the topsheet. Each barrier leg cuff 34 maycomprise one, two or more elastic strings 35 close to this free terminaledge 66 to provide a better seal.

In addition to the barrier leg cuffs 34, the article may comprisegasketing cuffs 32, which are formed in the same plane as the chassis ofabsorbent article, in particular may be at least partially enclosedbetween the topsheet and the backsheet, and may be placed laterallyoutwardly relative to the barrier leg cuffs 34. The gasketing cuffs 32can provide a better seal around the thighs of the wearer. Usually eachgasketing leg cuff 32 will comprise one or more elastic string orelastic element 33 comprised in the chassis of the diaper for examplebetween the topsheet and backsheet in the area of the leg openings.

U.S. Pat. No. 3,860,003 describes a disposable diaper which provides acontractible leg opening having a side flap and one or more elasticmembers to provide an elasticized leg cuff (a gasketing cuff). U.S. Pat.No. 4,808,178 (Aziz) and U.S. Pat. No. 4,909,803 (Aziz) describedisposable diapers having “stand-up” elasticized flaps (rier leg cuffs)which improve the containment of the leg regions. U.S. Pat. No.4,695,278 (Lawson) and U.S. Pat. No. 4,795,454 (Dragoo) describedisposable diapers having dual cuffs, including gasketing cuffs and rierleg cuffs. All or a portion of the rier leg and/or gasketing cuffs maybe treated with a lotion.

Elastic Waist Feature

The absorbent article may also comprise at least one elastic waistfeature (not represented) that helps to provide improved fit andcontainment. The elastic waist feature is generally intended toelastically expand and contract to dynamically fit the wearer's waist.The elastic waist feature preferably extends at least longitudinallyoutwardly from at least one waist edge of the absorbent core 28 andgenerally forms at least a portion of the back side of the absorbentarticle. Disposable diapers can be constructed so as to have two elasticwaist features, one positioned in the front waist region and onepositioned in the back waist region. The elastic waist feature may beconstructed in a number of different configurations including thosedescribed in U.S. Pat. No. 4,515,595, U.S. Pat. No. 4,710,189, U.S. Pat.No. 5,151,092 and U.S. Pat. No. 5,221,274.

Relations Between the Layers and Components

Typically, adjacent layers will be joined together using conventionalbonding method such as adhesive coating via slot coating or spraying onthe whole or part of the surface of the layer, or thermo-bonding, orpressure bonding or combinations thereof. Most of the bonding betweencomponents is for clarity and readability not represented in the Figure.Bonding between the layers of the article should be considered to bepresent unless specifically excluded. Adhesives may be typically used toimprove the adhesion of the different layers, for example between thebacksheet and the core wrap. The adhesives used may be any standardhotmelt glue as known in the art.

Test Procedures

The values indicated herein are measured according to the methodsindicated herein below, unless specified otherwise. All measurements areperformed at 21° C.±2° C. and 50%±20% RH, unless specified otherwise.All samples should be kept at least 24 hours in these conditions toequilibrate before conducting the tests, unless indicated otherwise. Allmeasurements should be reproduced on at least 4 samples and the averagevalue obtained indicated, unless otherwise indicated.

Centrifuge Retention Capacity (CRC)

The CRC measures the liquid absorbed by the superabsorbent polymerparticles for free swelling in excess liquid. The CRC is measuredaccording to EDANA method WSP 241.2-05.

Dry Absorbent Core Caliper Test

This test may be used to measure the caliper of the absorbent core(before use i.e. without fluid loading) in a standardized manner.

Equipment: Mitutoyo manual caliper gauge with a resolution of 0.01 mm,or equivalent instrument.

Contact Foot: Flat circular foot with a diameter of 17.0 mm (±0.2 mm). Acircular weight may be applied to the foot (e.g., a weight with a slotto facilitate application around the instrument shaft) to achieve thetarget weight. The total weight of foot and added weight (includingshaft) is selected to provide 2.07 kPa (0.30 psi) of pressure to thesample.

The caliper gauge is mounted with the lower surface of the contact footin an horizontal plane so that the lower surface of the contact footcontacts the center of the flat horizontal upper surface of a base plateapproximately 20×25 cm. The gauge is set to read zero with the contactfoot resting on the base plate.

Ruler: Calibrated metal ruler graduated in mm.

Stopwatch: Accuracy 1 second.

Sample preparation: The core is conditioned at least 24 hours asindicated above.

Measurement procedure: The core is laid flat with the bottom side, i.e.the side intended to be placed towards the backsheet in the finishedarticle facing down. The point of measurement (if not otherwiseindicated the crotch point C) is carefully drawn on the top side of thecore taking care not to compress or deform the core.

The contact foot of the caliper gauge is raised and the core is placedflat on the base plate of the caliper gauge with the top side of thecore up so that when lowered, the center of the foot is on the markedmeasuring point.

The foot is gently lowered onto the article and released (ensurecalibration to “0” prior to the start of the measurement). The calipervalue is read to the nearest 0.01 mm, 10 seconds after the foot isreleased.

The procedure is repeated for each measuring point. If there is a foldat the measuring point, the measurement is done in the closest area tothis point but without any folds. Ten articles are measured in thismanner for a given product and the average caliper is calculated andreported with an accuracy of one tenth mm.

Absorbent Article Caliper Test

The Absorbent Article Caliper Test can be performed as for the DryAbsorbent Core Caliper Test with the difference that the caliper of thefinished absorbent article is measured instead of the caliper of thecore. If not otherwise indicated, the point of measurement may be theintersection of the longitudinal axis 80′ and transversal axis 90′ ofthe absorbent article. If the absorbent articles were provided foldedand/or in a package, the articles to be measured are unfolded and/orremoved from the center area of the package. If the package containsmore than 4 articles, the outer most two articles on each side of thepackage are not used in the testing. If the package contains more than 4but fewer than 14 articles, then more than one package of articles isrequired to complete the testing. If the package contains 14 or morearticles, then only one package of articles is required to perform thetesting. If the package contains 4 or fewer articles then all articlesin the package are measured and multiple packages are required toperform the measurement. Caliper readings should be taken 24±1 hoursafter the article is removed from the package, unfolded and conditioned.Physical manipulation of product should be minimal and restricted onlyto necessary sample preparation.

Any elastic components of the article that prevent the article frombeing laid flat under the caliper foot are cut or removed. These mayinclude leg cuffs or waistbands. Pant-type articles are opened or cutalong the side seams as necessary. Apply sufficient tension to flattenout any folds/wrinkles Care is taken to avoid touching and/orcompressing the area of measurement.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application and any patent application or patent to which thisapplication claims priority or benefit thereof, is hereby incorporatedherein by reference in its entirety unless expressly excluded orotherwise limited. The citation of any document is not an admission thatit is prior art with respect to any invention disclosed or claimedherein or that it alone, or in any combination with any other referenceor references, teaches, suggests or discloses any such invention.Further, to the extent that any meaning or definition of a term in thisdocument conflicts with any meaning or definition of the same term in adocument incorporated by reference, the meaning or definition assignedto that term in this document shall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A substantially planar absorbent core extendingin a transversal direction and a longitudinal direction, and comprisinga core wrap enclosing an absorbent material substantially free ofcellulose fibers, the absorbent material forming a pattern of discreteabsorbent material areas which comprises transversally-orientated areasand longitudinally-orientated areas.
 2. The absorbent core of claim 1,wherein the absorbent core comprises a longitudinal axis, a frontregion, a middle region and a back region, these three regions being ofequal length in the longitudinal direction as measured on thelongitudinal axis, and at least some of the transversally-orientatedareas are comprised in at least one of the back third region and thefront third region.
 3. The absorbent core of claim 2, wherein at leastsome of the longitudinally-orientated areas are comprised in the middlethird region of the absorbent core.
 4. The absorbent core of claim 1,further comprising dot-like areas, each dot-like areas having alongitudinal dimension as measured by projection on a line parallel tothe longitudinal direction and a transversal dimension as measured byprojection on a line parallel to the transversal direction, and theratio of the longitudinal dimension to the transversal direction rangesfrom about 0.5 to about 2.0.
 5. The absorbent core of claim 1, whereinat least some of the transversally-orientated areas have a dimension inthe transversal direction which is at least about 20% of the width ofthe absorbent core.
 6. The absorbent core of claim 5, wherein at leastsome of the transversally-orientated areas have a dimension in thetransversal direction which is from about 25% to about 99% of the widthof the absorbent core.
 7. The absorbent core of claim 1, wherein atleast some of the longitudinally-orientated areas have a dimension inthe longitudinal direction which is at least about 15% of the length ofthe absorbent core.
 8. The absorbent core of claim 1, wherein theabsorbent material consists of superabsorbent polymer particles.
 9. Theabsorbent core of claim 1, wherein the core wrap comprises a firstsubstrate and a second substrate and the substrates are C-wrap bondedalong the longitudinal side edges of the absorbent core.
 10. Theabsorbent core of claim 1, wherein the absorbent material ismacroscopically profiled in the longitudinal direction.
 11. Theabsorbent core of claim 11, wherein the basis weight of the absorbentmaterial is higher in the middle third region of the core than in thefront third region or back third region.
 12. The absorbent core of claim1, further comprising a thermoplastic adhesive material to immobilize atleast some of the absorbent material within the core wrap.
 13. Theabsorbent core of claim 13 comprising an auxiliary glue on one of theinner side of the top side of the core wrap or the bottom side of thecore wrap.
 14. The absorbent core of claim 13, comprising a microfibrousglue.
 15. The absorbent core of claim 1, comprising at least twolongitudinally-orientated channel-forming areas, each channel-formingarea being substantially free of absorbent material and through whichthe top side of the core wrap is attached to the bottom side of the corewrap by a core wrap bond, so that when the absorbent material adjacenteach channel-forming area absorbs a fluid and swells, athree-dimensional channel are formed along the core wrap bond.
 16. Theabsorbent core of claim 15, wherein the two longitudinally-orientatedchannel-forming areas are mirror image of each other relative to thelongitudinal axis and are concave towards the longitudinal axis.
 17. Theabsorbent core of claim 15, wherein at least some of thelongitudinally-orientated areas are adjacent the channel-forming areasand run parallel to these channel-forming areas.
 18. A method for makingthe absorbent core of claim 1, the method comprising the steps of:providing a printing roll comprising a plurality of cavities, providinga lay-on drum, wherein the lay-on drum comprises at least one receptaclecomprising a support grid having longitudinally-oriented depressions andtransversally-oriented depressions, transferring a substrate to thelay-on drum; filling the cavities of the printing roll with an absorbentmaterial, bringing the receptacle with the supported substrate to adeposition area, depositing the absorbent material from the cavities ofthe printing roll onto the substrate while the substrate is supported bythe lay-on drum, wherein the material is deposited in the areas of thesubstrate corresponding to the depressions of the receptacle so that thedeposited absorbent material forms a pattern of transversally-orientatedareas and longitudinally-orientated areas; and forming a core wrapenclosing the deposited absorbent material, the core wrap comprising thefirst substrate.
 19. The method of claim 18 wherein the printing rollcomprises one or more cavity-free areas that collaborate with one ormore mating strips on the lay-on drum to form at least one absorbentmaterial-free area within the core wrap, and wherein the method furthercomprises the steps of: applying pressure between the top side and thebottom side of the core wrap at the absorbent material free-area to forma core wrap bond thus forming a channel-forming area.
 20. An absorbentarticle comprising the absorbent of claim 1.